Scientists have long known that animals' farts and poop contribute to global warming but findings of a new study have suggested that researchers may have underestimated the impact of methane emissions from livestock on climate change.
Methane And Global Warming
Methane, a principal component of farts, is a natural byproduct of digestion produced when microbes in the animal's gut break down and ferment food.
Methane is a gas known to contribute to the greenhouse effect, which traps the heat within the Earth's atmosphere and contributes to climate change. While carbon dioxide is often blamed for global warming, methane is actually 85 times more potent when it comes to trapping heat.
Sources of methane are varied. Some come from natural sources such as marshes and other wetlands but a bulk of methane emission comes from human activities that include cattle operations.
"We update information for cattle and swine by region, based on reported recent changes in animal body mass, feed quality and quantity, milk productivity, and management of animals and manure," the researchers wrote in their study. "We then use this updated information to calculate new livestock methane emissions factors for enteric fermentation in cattle, and for manure management in cattle and swine."
Previous Estimates Off By 11 Percent
Researchers of the new study made new calculations on how methane emissions from animals contribute to global warming. Taking into account the changes in the way humans use and keep livestock, they found that previous estimates that served as basis for the 2006 Intergovernmental Panel on Climate Change, were off by 11 percent.
USDA plant physiologist Julie Wolf and colleagues reevaluated the data that were used to calculate the IPCC 2006 methane emissions estimates. These estimates were based on relatively modest rates of increase in methane emission from 2000 to 2006 but things dramatically changed after this period as methane emission increased by 10-fold over the next decade.
"In many regions, livestock numbers are changing, and breeding has resulted in larger animals with higher intakes of food," Wolf said. "This, along with changes in livestock management, can lead to higher methane emissions."
The study, which has been published in the journal Carbon Balance and Management, also showed that methane is responsible for about 16 percent of global greenhouse gas emissions in 2006. Besides cattle operations, other human activities such as the production and transport of oil, coal and gas, as well as the decay of organic waste contribute to methane emissions.
